Some of the Dev of Kickstarter projects told me GOG do not support additional key for KS backer, also some of the game I purchased (Eschalon 2) before offer me steam key instead of GOG key (harder to give). I also give up on waiting Dev's Desktop Dungeon GOG key after 1 year and buy again myself here. (I admit not so happy)

This make me wonder should we give away more GOG Keys? Are we too stingy with that? Take a look in humble store now, I think 95% of the games are having steam keys but I think only Defender Quest have GOG Key to offer.

I am not sure if GOG.com will have a big lost financially if we are more generous in GOG Keys, but If someone gain a free GOG key for sure he will sign up GOG and claim. For me, that is a huge long term business gain unless that person is not buying any game thereafter. This must better than the temporarily financial lost.

Just my thought.

I want to think it's something that would not have escaped GOG attention and that they have done the math.

It's likely the volume of users here is not large enought yet.

Hmm,
I know when I backed the Dreamfall Chapters Kickstarter, I was given a GOG key (and any backer could, if they requested it)...
I wonder how it worked there.

GOG gives the developers keys for their own games if they request them. I received some GOG keys from developers when I asked. However, the whole process is manual so I need to email them and send some proof of purchase, they need to email GOG to get keys, then they need to email me a key. Since there is quite a bit of effort involved (especially if many people ask them for keys!) only very few developers do this since there is no return for the effort.

My guess is that Steam has the whole process automated so it is far easier (basically 0 hassle and effort beyond the initial setup) to give Steam keys out.

Not sure what that means. I know I got GOG keys from several projects, an I'm pretty sure I can choose a GOG key for both my Wasteland 2 copies (although I picked only one so far, for gifting).

Not counting Broken Age, Leisure Suit Larry Reloaded and Wings remake, I have always gotten GOG keys.
Sooner or later.
Usually later, when compared with Steam keys, but still I have received them.

And yes, in more than one case I needed to PM the Kickstarter people to send those. But the only time I have heard about problems with GOG keys have been the Wings remake, which promised GOG keys for the old Wings "next week" like half a year ago, but they still haven't been distributed, and they also said that because of their publisher they can't get any keys for the new one. Of course they never promised GOG keys either to begin with.

What do you mean by "additional"?
An extra key for those who already have gotten a steam key? Or just more keys for the backers?

I got a GOG Key for Divinity: Original Sin, and reading through this thread so far many other kickstarter projects also managed to give out keys, so there must be some kind of support for GOG keys...

gOg keys sold within gOg = gOg get 30%
gOg keys sold outside gOg = gOg get 0%